1. Field of the Invention
The present invention relates to a magnetic film used as, for example, a magnetic pole portion of a recording inductive head. In particular, the present invention relates to a magnetic film which is composed of Co and Fe, which contains no impurity, and which can improve both the saturation magnetic flux density and the corrosion resistance by microcrystallization, a thin film magnetic head using this magnetic film, a method for manufacturing the above-mentioned magnetic film and a method for manufacturing the above-mentioned thin film magnetic head.
2. Description of the Related Art
In particular, in order to match a future increase in packing density, a magnetic material having a high saturation magnetic flux density Bs must be used for components such as a core layer of a thin film magnetic head, and thereby, magnetic fluxes must be concentrated in the vicinity of the gap of the above-mentioned core layer to improve the packing density.
Conventionally, alloys containing Co and Fe have been frequently used for the above-mentioned magnetic material. Such materials are described, for example, in the following Japanese patents and published patent applications.
Japanese Patent No. 3298930
Japanese Unexamined Patent Application Publication No. 7-57934
[Patent literature 3]
Japanese Unexamined Patent Application Publication No. 7-233494
[Patent literature 4]
Japanese Unexamined Patent Application Publication No. 2002-134318
[Patent literature 5]
Japanese Unexamined Patent Application Publication No. 2002-217029
When a magnetic material containing Co and Fe is formed by plating, in general, sodium saccharin (C6H4CONNaSO2) is added to the plating bath as a brightener (refer to, for example, Patent literature 2 and Patent literature 4). When sodium saccharin is added to a plating bath, however, S (sulfur) an impurity, in the sodium saccharin mixes with Fe and corrosion is likely to occur. Furthermore, increased concentrations of trivalent Fe ions and Fe(OH)3 in the plating bath reduce the saturation magnetic flux density Bs when Fe ions from these compounds are taken into a plated film. In order to reduce corrosion of the above-mentioned magnetic material, a noble metal that is unlikely to be ionized can be added to the plating bath so as to form a CoFeα (α represents, for example, Rh) alloy. The CoFeα alloy reduces the corrosion described above compared with the case where no noble metal element α is added. On the other hand, the saturation magnetic flux density Bs is reduced an available saturation magnetic flux density on the order of 2.2 T.
A saturation magnetic flux density Bs on the order of 2.4 T can potentially be produced in a bulk material composed of Co and Fe. Therefore, it is desired that a saturation magnetic flux density Bs of 2.4 T or close to this value be achieved through a plating process. However, it was conventionally difficult to form the magnetic material containing Co and Fe by plating, while creating a magnetic material having a high saturation magnetic flux density Bs and high corrosion resistance.